# turbine aerodynamics for time independet computing

Hello everyone,

Is that possible to perform a simulation with FAST & Aerodyn for computing turbine aerodynamics independent of dynamic (Time) coupling, so that at the end the thrust coefficient (CT), and torque coefficient (CQ) are independent for each operation point and as only a function of tip-speed ratio (TSR) and blade-pitch angle?
I tried to modify the AeroDyn input file in this way so that No DS (Dynamic Stall), No Prandtl tip-&hub-loss, and No tangential-&axial-induction Calculation as Follows:
But the result was not as I expected!

Sebastian Hippel

Dear Sebastian,

You can use the standalone driver for AeroDyn v15 to calculate the surface of power, torque, thrust (etc.) coefficient versus tip-speed ratio and blade-pitch angle. See the following forum topic of more information: http://forums.nrel.gov/t/aerodyn-v15-04-with-parametric-analysis/1765/2 (this assumes a rigid rotor).

Best regards,

Dear Jason,

Thank you very much for the fast replay,

Actually I wanted to ask you from my previous question if it’s possible with AeroDyn to deactivate the aerodynamic inertia. For this reason I looked for the aerodynamic effects which could include this air inertia. What I think the most inertia of the air could be included in Dynamic Stall and Wake after the wind turbine. Therefore I set WakeMod to 1, AFAeroMod to 1, FrozenWake to True and TippLoss & HubLoss to False, and I thought in this way I linearize the wind flow and the Waks and the Dynamic Stall will be deactivated. But the Problem when I do this modification in AeroDyn input-file I didn’t get the results that I can say the wind flow is linearized and the aerodynamic coefficient are no more dynamic computed.

I would like to know more what happened when I selected steady model (AFAeroMod =1).

Best regards,
Sebastian Hippel

Dear Sebastian,

With WakeMod = 1, the wake/induction will be computed quasi-statically (without dynamics e.g. delays between load and induction) using blade-element/momentum (BEM) theory.

With AFAeroMod = 1, the airfoil aerodynamics will be computed quasi-statically (without unsteady dynamics e.g. hysteresis loops) using table look-up aerodynamics based on the specified airfoil polar data.

But if the local wind at the airfoil is changing every time step (e.g. as a result of shear, shaft tilt, yaw error) then both of these models will recompute the quasi-static loads every time step (so e.g. the aerodynamic loads will still change with time). Only if you eliminate all variations in local inflow to the airfoil will the result be purely stationary. You could of course azimuth-average the periodic solution over one rotor revolution to get an effective “mean” response.

Please note that the FrozenWake switch is only used by AeroDyn when linearization is invoked by a FAST linearization analysis (FrozenWake is not used by the standalone AeroDyn driver).

Best regards,